AMD64 UEFI loader: staging area: seeking a summary overview of D31121 and related bug reports

<https://reviews.freebsd.org/D31121>

Amongst the related bug reports, 
<https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=209821#c48>:

* suspects some kind of "special behaviour" with ASUS UEFI

* also observes a regression in FreeBSD.

Given other related bugs, which include 
<https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=255073> (mostly HP, 
one Samsung):

* please, can anyone offer a summary overview of the underlying situations?

Something not-too-technical will be ideal.

In particular, I'd like to counter an (off-list) implication that bugs 
such as these are simply the result of computer manufacturers' products 
not following "the standards".

(Re: 
<https://en.wikipedia.org/wiki/Unified_Extensible_Firmware_Interface> 
and so on, I do understand that complexities exist, however "the 
standards" is, for me, too sweeping a phrase; it's non-specific.)

TIA, thanks also to everyone who is helping towards the fixes.